Relative position determination between lunar lander and rover using same beam VLBI technique

Introduction: In China's third lunar exploration project Chang'E-3 mission, a lander and a rover will be placed on the lunar surface. The lander will not be movable, and the rover will explore the Moon automatically. The rover will be in moving and standstill state interchangeably [1].The precise positioning of the lander and the rover is very important in Chang'E-3 mission. This paper focuses on the relative position determination between the lander and the rover (when at standstill) using same beam VLBI technique. In mul-ti-frequency same beam VLBI observations, two explorers with small separation angles are observed simultaneously with the main beam of the receiving telescopes (Figure 1). Because the separation angle of the two explorers is small, the influences of the atmosphere, the ionosphere and the time delay in the instruments are almost canceled from the difference in the correlation phase, thus high accuracy differential VLBI delay can be achieved [1]. The relative position between the lander and the rover on the lunar surface can thus be determined precisely by using the differential VLBI delay. Simulation work for Chang'E-3 mission is implemented , and the result shows that the relative position between the lander and the rover will be better than 50 m.